1. Field of the Invention
This invention relates to a conveyor belt drip pan apparatus for receiving falling debris removed from the conveyor belt and transferring the debris to a receiving area.
2. Description of the Prior Art
Conveyor belts are widely used for transporting aggregate material such as coal, mineral ores, and other materials. Oftentimes some of the material will cling to the surface of the conveyor belt and be carried on the return run of the belt. The clinging material is referred to as carry back material or debris and must be removed from the belt to avoid possible damage or reduce the carrying capacity of the conveyor belt to convey the aggregate material thereby reducing operating efficiency. Various scraping methods and systems have been designed to scrape and remove the debris from the conveyor belt and onto another conveyor or the surface below the conveyor belt. Belt scraper devices are located on the unloaded strand or return run of the conveyor belt usually near the discharge point of the conveyor. The scraper device cleans the belt of the debris. If not cleaned, the debris may fall from the belt and if accumulated enough may interfere with the movement of the conveyor belt. Reference is made to U.S. Pat. Nos. 4,189,046 and 4,768,645, and the references cited therein which disclose known or proposed designs of conveyor belt scraper apparatus. Systems for receiving the scraped debris from a conveyor belt are known where the debris is received on a receiving belt or a drip pan or deck frame arranged below the conveyor belt and the debris transported from the receiving belt or deck frame onto a receiving or scavenger conveyor or bin. A drip pan system known in the art uses a scraping blade that is powered by a hydraulic ram to reciprocate on the drip pan to scrape off the debris. The scraping blade is retuned to a point and reciprocated again in the scraping direction. The reciprocating cycle is controlled automatically using proximity sensors to sense the need to reverse the scraping blade movement. The hydraulic ram scraping mechanism uses a scraping blade that relies solely on the bending strength of the actuating rod connection to the scraping blade. The rod connection is vulnerable to damage when the scraping blade is pushing a non-uniform load. Also, the known conveyor blade drip pan apparatus is limited in that the scraping blade travel is based on the maximum available length of the actuating cylinder rod stroke. In other words, the existing drip pan scraping system has no provision for extending the length of the drip pan arrangement and the length of scraping travel. The existing drip pan scraping system relies on a cam arrangement, exposed to the sometimes wet debris, to rotate the scraping blade to a position above the surface of the drip pan. The cam arrangement relies on friction of the drip pan surface to rotate the scraping blade. When friction is reduced due to moisture, for example, the scraping blade might not rotate and remain in engagement with the drip pan surface and debris will be dragged backwards on the return stroke of the scraping blade, clogging the drip pan, interfering with the effectiveness of removing the debris, or resulting in the debris being deposited on the surface area below the conveyor. It is not popularly used.
Another debris removing and transporting system uses a chain and flight arrangement to scrape and drag conveyor belt debris. The chain is driven on a powered sprocket with the flights scraping and transporting the debris to a removal area. The chain and flight scraping arrangement uses a significant number of moving parts is inefficient and unreliable.
The present invention overcomes the problems inherent in known conveyor belt drip pan apparatus by providing an apparatus which incorporates a scraper assembly having a scraper blade integrally stabilized to engage a drip pan or deck frame to scrape non-uniform loads and not rely solely on the bending strength of an actuating rod connection to the scraper blade. This invention also provides scraper blade movement on its return stroke which is positive, lifting the scraper blade above the deck frame surface without relying on friction forces required by cam rotating arrangement. This invention also allows scraper blade and deck frame extensions without need for modifying or changing the scraper blade movement power source. This invention applies a remotely located arrangement to control the movement cycle of the scraper blade avoiding exposure of sensing devises to debris environment. This invention overcomes this problem inherent in existing conveyor belt drip pan assemblies with few moving parts increasing its efficiency and reliability.